diff --git a/helpers/derhelpers/derhelpers-legacy.go b/helpers/derhelpers/derhelpers-legacy.go
deleted file mode 100644
index a634a46eb..000000000
--- a/helpers/derhelpers/derhelpers-legacy.go
+++ /dev/null
@@ -1,50 +0,0 @@
-// +build !go1.13
-
-// Package derhelpers implements common functionality
-// on DER encoded data
-package derhelpers
-
-import (
-	"crypto"
-	"crypto/ecdsa"
-	"crypto/rsa"
-	"crypto/x509"
-
-	cferr "github.com/cloudflare/cfssl/errors"
-	"golang.org/x/crypto/ed25519"
-)
-
-// ParsePrivateKeyDER parses a PKCS #1, PKCS #8, ECDSA, or Ed25519 DER-encoded
-// private key. The key must not be in PEM format.
-func ParsePrivateKeyDER(keyDER []byte) (key crypto.Signer, err error) {
-	generalKey, err := x509.ParsePKCS8PrivateKey(keyDER)
-	if err != nil {
-		generalKey, err = x509.ParsePKCS1PrivateKey(keyDER)
-		if err != nil {
-			generalKey, err = x509.ParseECPrivateKey(keyDER)
-			if err != nil {
-				generalKey, err = ParseEd25519PrivateKey(keyDER)
-				if err != nil {
-					// We don't include the actual error into
-					// the final error. The reason might be
-					// we don't want to leak any info about
-					// the private key.
-					return nil, cferr.New(cferr.PrivateKeyError,
-						cferr.ParseFailed)
-				}
-			}
-		}
-	}
-
-	switch generalKey.(type) {
-	case *rsa.PrivateKey:
-		return generalKey.(*rsa.PrivateKey), nil
-	case *ecdsa.PrivateKey:
-		return generalKey.(*ecdsa.PrivateKey), nil
-	case ed25519.PrivateKey:
-		return generalKey.(ed25519.PrivateKey), nil
-	}
-
-	// should never reach here
-	return nil, cferr.New(cferr.PrivateKeyError, cferr.ParseFailed)
-}
diff --git a/helpers/derhelpers/derhelpers.go b/helpers/derhelpers/derhelpers.go
index 25bda27a5..561691be2 100644
--- a/helpers/derhelpers/derhelpers.go
+++ b/helpers/derhelpers/derhelpers.go
@@ -1,5 +1,3 @@
-// +build go1.13
-
 // Package derhelpers implements common functionality
 // on DER encoded data
 package derhelpers
diff --git a/helpers/derhelpers/ed25519.go b/helpers/derhelpers/ed25519.go
index eb669ce93..bf20dc206 100644
--- a/helpers/derhelpers/ed25519.go
+++ b/helpers/derhelpers/ed25519.go
@@ -2,11 +2,10 @@ package derhelpers
 
 import (
 	"crypto"
+	"crypto/ed25519"
 	"crypto/x509/pkix"
 	"encoding/asn1"
 	"errors"
-
-	"golang.org/x/crypto/ed25519"
 )
 
 var errEd25519WrongID = errors.New("incorrect object identifier")
diff --git a/helpers/derhelpers/ed25519_test.go b/helpers/derhelpers/ed25519_test.go
index 629d12eef..4a639de59 100644
--- a/helpers/derhelpers/ed25519_test.go
+++ b/helpers/derhelpers/ed25519_test.go
@@ -2,10 +2,9 @@ package derhelpers
 
 import (
 	"bytes"
+	"crypto/ed25519"
 	"encoding/pem"
 	"testing"
-
-	"golang.org/x/crypto/ed25519"
 )
 
 var testPubKey = `-----BEGIN PUBLIC KEY-----